function changeImg() {  
      var imgSrc = $("#imgObj");  
      var src = imgSrc.attr("src");  
      imgSrc.attr("src", chgUrl(src));  
      //时间戳  
      //为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳  
      function chgUrl(url) {  
          var timestamp = (new Date()).valueOf();  
          urlurl = url.substring(0, 17);  
         if ((url.indexOf("?") >= 0)) {  
             urlurl = url + "&t=" + timestamp;  
         } else {  
             urlurl = url + "?t=" + timestamp;  
         }  
         return urlurl;  
     }  
}  
function isRightCode() {  
     var code = $("#veryCode").attr("value");  
   
     $.ajax({  
         type:"POST",  
         url:"/image.do?method=validate",  
         data:"c="+code,  
         success:callback  
     });  
} 

function callback(data) {  
     $("#info").html(data);  
} 